Stage 2 of DPT-1 is the second phase of a nationwide NIH funded study designed to identify and treat individuals who have an increased risk of developing Insulin Dependent Diabetes Mellitus. The goal of DPT-1 is to assess if treatment with an oral antigen (capsules of recombinant human insulin or recombinant human glutamic acid decarboxylas taken by volunteers with an intermediate risk of developing IDDM) or a parenteral antigen (low dose insulin taken by volunteers with a high risk of developing IDM) will prevent or slow the onset of IDDM. first degree relatives and some second degree relatives of patients with IDDM have had blood tests to detect the presence of islet cell antibodies (ICA). Those relatives with positive ICA results and interest in further participation in DPT-1 will be invited to participate in the second phase of the prevention study, Staging. Eligible volunteers will follow up at the Diabetes Center for three visits. An intrevenous glucose tolerance test (IVGTT) will be performed. If the result shows a diminished first phase insulin response a second IVGTT will be completed. Volunteers will also undergo an oral glucose tolerance test. Blood samples will be obtained to identify immune system changes and genetic markers which may predict the development of IDDM. Results of the staging phase of DPT-1 will enable investigators to determine the volunteers degree of risk for IDDM and eligibility for the oral antigen or the parenteral antigen intervention. Volunteers interested in participating in the treatment phase of DPT-1 will be referred to the nearest clinical center conducting the double-blind placebo controlled interventions.